Water recreational areas, such as swimming pools, shorelines, docks, water parks and the like can be dangerous places. According to the U.S. Consumer Product Safety Council, for example, each year emergency departments report hundreds of drowning deaths and thousands of near-drowning incidents among children under age 5 years in residential swimming pools in the U.S. Although there are pool alarms that sound off if someone enters the water, those alarms may not detect or monitor normal swimming activity. The alarms may therefore be useful in detecting someone entering the water unexpectedly, but may not be useful in monitoring the pool when people are in the pool doing normal pool or swimming activities.
As a result, there is a need for a water activity monitoring system that can monitor normal water or swimming activities and determine, for example, whether someone has slipped underneath the water and stayed submerged for an unsafe amount of time.